This invention relates to tire monitoring systems particularly to wireless systems for indicating tire temperature and pressure on a display unit mounted within a motor vehicle.
The system which is described hereinafter is called the SENSATEC.TM. tire monitoring system. Other tire monitoring systems, such as the Fleet Specialties product, cannot provide internal tire temperature but rather measure gross pressure variation and are dedicated to a particular tire. The unit cannot be switched to another tire nor is it possible to measure temperature.
Another commercial tire monitoring unit is manufactured by Kisan Corporation which employs a transducer with a pick-up coil to generate a magnetic field producing a signal whose strength varies with tire pressure. The system requires replacement of the typical valve stem.
The prior art also includes U.S. Pat. No. 4,954,677 to Alberter, et al which comprises a tire pressure sensor including a reference gas pressure chamber and an electrically conductive diaphragm for activating a sensor circuit when the pressure is at a predetermined value.
U.S. Pat. No. 4,529,961 to Nishimura, et al employs a Bourdon tube which deforms with pressure to provide a signal. Bowler U.S. Pat. Nos. 5,231,872 and 5,335,540 describe a complicated tire monitoring apparatus for monitoring trucks while in use.
Other patents of interest include Brown U.S. Pat. No. 4,978,941 on a truck tire monitor and U.S. Pat. No. 5,035,137 to Burkard Also included are U.S. Pat. Nos. 4,966,034; 5,071,259; 5,140,851; and, 5,230,243.
The present inventions discloses a unique tire pressure and temperature monitor suitable for use on automobiles, trucks or other apparatus utilizing pneumatic tires.